Position detection switches have many applications. For example, a laptop or notebook computer typically includes a lid switch that triggers a sleep state when the lid of the device, which typically comprises the display of the device, is closed. FIG. 1 illustrates an embodiment of the general clamshell mechanical configuration of a notebook computer. As depicted, notebook computer 100 comprises a display plane 102 and a keyboard/control electronics plane 104. Planes 102 and 104 are hinged, allowing display plane 102 to be closed down onto keyboard plane 104 when the notebook computer is not being used. An open or closed state of notebook computer 100 is typically indicated by the state of a switch associated with planes 102 and 104. The state of the switch changes based on the positions of planes 102 and 104 relative to one another.
Existing lid switches most commonly comprise Hall Effect switches. Hall Effect switches require a magnet to be placed on either plane 102 or plane 104 and a sensor to be placed on the opposing plane. The magnet comprises a three-dimensional volume and may comprise an undesirable form factor, especially if placed on plane 102 since it may affect the maximum achievable active area of the display. However, more difficult routing may result if the magnet is instead placed on plane 104 and the sensor is placed on plane 102 since in such cases the signal from the sensor on plane 102 needs to be routed through the clamshell hinge to electronics on plane 104. Furthermore, the magnet of a Hall Effect switch may produce an undesirable magnetic field. The magnetic field may detrimentally affect certain functions associated with notebook computer 100, such as those requiring a compass. Moreover, magnets are relatively expensive components and require special processing and handling during manufacturing. Other commonly employed switches include mechanical displacement switches and optical beam interruption switches. Such switches may present similar form factor, routing, and manufacturing issues as Hall Effect switches and may also be affected by foreign object contaminations.